A good understanding of root water uptake is important to develop modern and environmental friendly irrigation and fertilization systems. One way to quantify root water uptake at the field scale is the water mass balance. Temporal Domain Reflectometry (TDR) has been used for many years to assess soil water content distribution. Yet, despite a very good temporal resolution, they suffer from their low spatial resolution. On the other hand, Electrical Resistivity Tomography (ERT) can provide the 3D distribution of soil water content with a good spatial resolution but has a low temporal resolution due to the acquisition time. By combining these 2 techniques, it is possible to obtain the soil water content distribution with good spatial and temporal resolutions. This study was conducted to (i) compare soil water content obtained with TDR and ERT measurements in a Corn field during the growing season; (ii) estimate soil water content distribution with a high temporal and spatial resolution; and (iii) combine soil water content measurements to quantify root water uptake.

In July 2009, an experimental plot was installed in a Corn field and ERT and TDR measurements were performed between August 2009 and September 2009. Boundary conditions were monitored with tensiometers (for the drainage) and a meteorological station. The first results show comparable patterns of soil water content with TDR and ERT. In particular, it is possible to see the row/inter-row Corn pattern dynamics with both techniques. This is mainly visible during the dry periods where there is a decrease of soil water content under Corn rows especially due to root water uptake.